664999949 has 2 divisors, whose sum is σ = 664999950. Its totient is φ = 664999948.

The previous prime is 664999939. The next prime is 665000027. The reversal of 664999949 is 949999466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 556110724 + 108889225 = 23582^2 + 10435^2 .

It is a cyclic number.

It is not a de Polignac number, because 664999949 - 2¹² = 664995853 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664999939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332499974 + 332499975.

It is an arithmetic number, because the mean of its divisors is an integer number (332499975).

Almost surely, 2^664999949 is an apocalyptic number.

It is an amenable number.

664999949 is a deficient number, since it is larger than the sum of its proper divisors (1).

664999949 is an equidigital number, since it uses as much as digits as its factorization.

664999949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34012224, while the sum is 65.

The square root of 664999949 is about 25787.5929276076. The cubic root of 664999949 is about 872.8518512051.

The spelling of 664999949 in words is "six hundred sixty-four million, nine hundred ninety-nine thousand, nine hundred forty-nine".